 They concluded that in the inner Port Shelter, the flushing time is the longest among the fish culture zones of Hong Kong, which is 40 days in the dry season.While Po Toi O is located at the mouth of Port Shelter, its hydrodynamics is mainly affected by the open ocean, thus the flushing time was just 5.3 days in dry season in the computer estimation.A research conducted in 2006, had recorded a total of 106 fish species in Port Shelter in their preliminary report, including rare species "Cephalopholis urodeta", "Bodianus axillaris" and "Echidna nebulosa".